Diterpenoid Metabolites of Cyathus helenae. Cyathin B3 and Cyathin C3

Abstract
Cyathin B3, a metabolite of Cyathus helenae is shown to possess structure 3a. Cyathin C3 is 1,2-dehydrocyathin B3 (4a). Cyathin B3 has been correlated with cyathin A3 (1) and cyathin C3 with allocyathin B3 (2).